Heat exchanger especially for nonstationary gas turbines

ABSTRACT

A heat exchanger in which one of the two media is conducted through tubes while the other medium flows externally along the tubes in counterflow principle. The tubes are arranged in several planes axially parallel to one another and the ends of the tubes, flattened off into rectangles, are combined in a common mounting for the connection of a group of tubes to a respective inlet or outlet aperture.

United States Patent Filed Eberhard Tletenbacher Ludwlgsburg, Germany Oct. 24, 1969 Dec. 14, 1971 Daimler-Benz Aktlengesellschalt Stuttgart-Unterturkhelm, Germany lnventor Appl. No.

Patented Assignee HEAT EXCHANGER, ESPECIALLY FOR NONSTATIONARY GAS TURBINES 8 Claims, 6 Drawing Figs.

U.S. C1 165/158, 29/157.4,165/165,165/166,165/175,165/178 Int. Cl F281 9/02 Field of Search 165/164,

[56] Reierences Cited UNITED STATES PATENTS 2,601,973 7/1952 Jensen... 165/166 3,204,693 9/1965 Kuhn 165/175 X 3,368,616 2/1968 Adams eta1..... 165/164 3,473,604 10/ 1 968 Tiefenbacher 165/166 FOREIGN PATENTS 838,466 6/1960 Great Britain 165/166 352,602 6/1905 France 165/153 Primary Examiner-Albert W. Davis, .1 r. A1torney-Craig, Antonelli and Hill ABSTRACT: A heat exchanger in which. one of the two media is conducted through tubes while the other medium flows externally'along the tubes in counterflow principle. The tubes are arranged in several planes axially parallel to one another and the ends of the tubes, flattened off into rectangles, are combined in a common mounting for the connection of a group of tubes to a respective inlet or outlet aperture.

Patented Dec. 14, 1971 FIG. (5v

7 INVENTOR EBERIHARD TIEFENBACHER fl dusuw dawuxvilbu i I 5 ATTORNEYS gamma The present invention relates to a heat exchanger, especially for nonstationary gas turbines, which consists of pipes arranged on the inside of a housing or the like, through which is conducted one of the two media participating in the heat exchange whereas the other medium moves externally along the pipes in counterflow.

The demand is made of heat exchanges for portable or nonstationary gas turbines that they are to be as light weight as possible and are to possess as small dimensions as possible. However, experience has demonstrated that this requirement can be fulfilled best if the heat exchangers are equipped with pipes and the media are conducted through the heat exchanger according to the counterflow principle. Heat exchangers operated countercurrent or counterflow possess, by reason of the favorable temperature distribution, a small heat-transferring surface and therewith a smaller volume and weight than other types of constructions. Nevertheless, the known types of constructions have proved still too heavy and too space consuming for different applications in nonstationary gas turbines, especially for the motor vehicle or the aircraft construction.

The present invention aims at creating a heat exchanger which possesses particularly small dimensions and low weight and which can be manufactured in a simple manner. Addi' tionally, a heat exchanger is to be created which, by reason of its construction, can be adapted without difficulties to the contours of housings or the like for the purpose of space saving and is utilizable in the form of structural units. The present invention essentially consists in bat the pipes or tubes are arranged axially parallel in several planes disposed one above the other or one adjacent the other and the ends thereof are respectively combined in a common end-face-mounting means for the connection of the group of tubes to a respective inlet or outlet aperture for the medium flowing through the tubes. Appropriately, provision may be made that the inlet and/or the outlet for the medium, not flowing through the tubes, is arranged laterally directly behind the end-face mounting means of the tube group and the ends ofthe tubes or pipes are flattened off within this area into rectangles. In this manner, wide inflow or outflow channels are formed within the area of the flattened off ends of the tubes which assure a rapid and good distribution of the medium moving externally along the tubes from the inlet toward the outlet. Furthermore, the tubes or pipes arranged in different planes can be held at spacings in a simple manner by bars abutting at the rectangles.

An extraordinarily favorable construction results if the rectangular ends of the tubes of each plane are disposed without gap adjacent one another. Such a type of construction is structurally very simple, on the one hand, because only very few individual parts differing from one another are necessary. Additionally, the pressure losses in the inflow and outflow part can be kept very small and the soldering or brazing operation can be simplified. It is particularly favorable if the end-facemounting means for the pipes or tubes are constructed directly as end face flanges for the housing of the heat exchanger.

ln order to achieve a favorable heat exchange, provision may be made that the tubes of two adjoining planes are mutually offset in the direction of these planes, preferably by the amount of the diameter of the tubes. Such an arrangement of the tubes produces uniform gaps between the tubes or pipes and therewith a uniform flow on the outside of the tubes so that extraordinarily favorable conditions exist for the heat transfer. It is thereby favorable if the thickness of the bars corresponds to the height of the rectangular ends of the tubes and if each second bar is bent back or folded back at its end. With such a type of bar, the different number of the tubes or pipes disposed mutually offset in adjacent planes can be compensated for.

Frequently it is necessary for reasons of rigidity to construct the outer housing of a heat exchanger curved. Provision may be made in connection therewith in an advantageous manner that the thickness of the bars corresponds to the height of the rectangular ends of the tubes, and each bar is bent back at its end. It is achieved by this measure that all bars can be manufactured with the same length whereas they can simultaneously compensate for the differences in the different planes provided with tubes. Furthermore, with this type of construction, an adaptation of the heat exchanger to the contours of engines or the like and therewith a space saving can be achieved.

The bars, for the purposes of securing at the housing and of easier assembly, may be advantageously provided at the ends thereof with slots, by means of which they engage into the flanges of the housing.

Accordingly, it is an object of the present invention to provide a heat exchanger, especially for nonstationary gas turbines, which avoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a heat exchanger which is of extreme light weight and small dimensions.

A further object of the present invention resides in a heat exchanger which is not only small in dimension and light in weight but which can also be manufactured in a simple manner.

Still a further object of the present invention resides in a heat exchanger that can be readily adapted to the contours of other structural parts.

These and further objects, features, and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein: Y

FIG. l is a somewhat schematic perspective view of a heat exchanger in accordance with the present invention, partially cut away;

FIG. 2 is a partial perspective view, partly cut away, of a modified embodiment of a heat exchanger in accordance with the present invention, which includes a particular type of securing of the spacer bars for the tubes at the housing flange;

FIG. 3 is a partial crosssectional view through the inlet or outlet channels within the heat exchanger constructed in accordance with the present invention and taken along line III- III in FIG. 2;

FIG. 4 is a somewhat schematic partial perspective view, partly cut away, of a modified embodiment of a heat exchanger in accordance with the present invention in which the tubes are mutually offset;

HO. 5 is a somewhat schematic elevational view of an arrangement of a heat exchanger in accordance with the present invention about a turbine; and

FIG. 6 is a somewhat schematic, partial elevational view of the securing of the tubes in a heat exchanger according to FIG. 5.

Referring now to the drawing where like reference numerals are used throughout the various views to designate like parts, and more particularly to FIG. 1, the pipes or tubes 2 are arranged axially parallel to one another on the inside of the heat exchanger housing l in several planes. The medium to be heated or cooled flows, for example, through the tubes 2 which are combined at the ends of the heat exchanger in a respective common, end-face-mounting means that is constructed as a flange of the housing. The heating or cooling medium flows in through an inlet 3 laterally directed to the rear of the end face flange of the heat exchanger and proceeds in counterflow to the medium to be heated or cooled up to the rear wall of the heat exchanger and is discharged thereat laterally through the outlet 4. The tubes 2 are flattened off rectangularly at the ends thereof within the areas of the inlet and outlet 3 and 4 of the medium to be heated or cooled and are arranged adjacent one another without gaps. The individual planes of the tubes are determined and arranged at predetermined distance to one another by spacer bars 5.

The bars 6 according to FIG. 2 are provided with slots 7 which engage in a flange 8 of the heat exchanger housing 1. A greater rigidity is achieved thereby and additionally a simplification is realized during the assembly while a better stability is assured during the transport and during the soldering or brazing in the furnace.

As can be readily seen from FIG. 3, relatively large interstices or intermediate spaces 9 are present between the individual planes of pipes or tubes 2 within the area of and outlet inlet and outlet apertures of the heating or cooling medium so that the medium can distribute itself unifonnly over the entire heat exchanger. The uppennost bar 10 is constructed with an inclined surface 11 for assembly reasons. This bar 10 may thus produce a clamping effect so that the assembly is simplified.

The tubes 12 of the heat exchanger according to H0. 4 are mutually offset in mutually adjoining planes. With such an offset arrangement more uniform intermediate spaces between the individual tubes 12 result so that a more favorable heat transfer is made possible. All bars 13 possess a thickness that corresponds to the height of the rectangularly flattened off tubes 12. Each second bar 13 is bent back or folded over at its end in order to be able to compensate for the difi'ering number of the tubes 12 of two adjacent planes. The bars 6, 13 are also slotted and are inserted with the slots thereof in a flange 8 of the heat exchanger housing.

FIG. 5 illustrates schematically the arrangement of a heat exchanger according to the present invention about a turbine 14. For that purpose, the exchanger is constructed curved. Advantageously also in this case the individual pipes 15 are arranged mutually offset in different planes.

As illustrated in FIG. 6, in the embodiment of FIG. 5, the bars 16 may also be bent back or folded back at the ends thereof in a structurally simple manner. The bars 16 thereby all possess the same length prior to their installation and assembly. For the purpose of securing at the heat exchanger housing 17, a slot 18 is milled into the bars which corresponds to the curvature of the heat exchanger housing. This slot 18 will be milled in only, when the bars 16 are already assembled into a structural unit. If one were to dispense with the bars, then each tube would have to be provided at the outer contour with a different curvature.

While I have shown and described only several embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are within the scope of those skilled in the art.

lclaim:

l. A heat exchanger comprising a housing, tube means arranged on the inside of said housing for conducting one of two fluid media participating in the heat exchange, the other fluid medium being conducted around the external surfaces of said tube means substantially in counterflow to said one fluid medium, said tube means being arranged axially parallel in a plurality of tube planes, each tube plane including a plurality of tube means with rectangular end openings in abutting relationship with the rectangular end openings of adjacent tube means, the rectangular end openings at one end ofsaid tube means terminating in a common plane where they are connected to a common collecting flange to form an inlet for said one fluid medium, the rectangular end openings at the other end of said tube means terminating in a common plane where they are connected to a common collecting flange to form an outlet for said one fluid medium, said tube planes being spaced from one another in parallel relationship by spacing strips extending transversely to the longitudinal extent of the tube means and arranged adjacent the respective rectangular end openings to form a tube floor for the tubes of one plane, said strips being of a thickness corresponding to the rectangular height of the tube ends and wherein alternate strips are folded over on themselves at their ends to abut the first tube means of the adjacent tube plane for staggering the tube means of one plane with respect to the tube means of another plane.

2. A heat exchanger according to claim 1, characterized in that said housing has a curved interior configuration in the area adjacent the respective ends of said spacing strips.

3. A heat exchanger according to claim 2, characterized in that the bar means are provided at the ends thereof with slots, by means of which they are adapted to be inserted into flange means at the housing means.

4. A heat exchanger according to claim 1, characterized in that the strips exhibit slots at their end for engagement with the collecting flanges of the housing and in that the outermost strip is provided with an inclined clamping surface to aid in the assembly of the tube means within the housing.

5. A heat exchanger according to claim 1, characterized in that inlet and outlet means for the other fluid medium are ar ranged laterally directly adjacent the bottoms of the rectangular cross section portion of the tube means.

6. A heat exchanger according to claim 4, characterized in that inlet and outlet means for the other fluid medium are arranged laterally directly adjacent the bottoms of the rectangular cross section portion of the tube means.

7. A heat exchanger according to claim 1, characterized in that each of the tube means is cylindrical along a substantial portion thereof and that the tube means of two adjacent planes are mutually offset by an amount corresponding to approximately the diameter of the tube means.

8. A heat-exchanger according to claim 7, characterized in that said housing has a curved interior configuration in the area adjacent the respective ends of said spacing strips.

I II III l k 

1. A heat exchanger comprising a housing, tube means arranged on the inside of said housing for conducting one of two fluid media participating in the heat exchange, the other fluid medium being conducted around the external surfaces of said tube means substantially in counterflow to said one fluid medium, said tube means being arranged axially parallel in a plurality of tube planes, each tube plane including a plurality of tube means with rectangular end openings in abutting relationship with the rectangular end openings of adjacent tube means, the rectangular end openings at one end of said tube means terminating in a common plane where they are connected to a common collecting flange to form an inlet for said one fluid medium, the rectangular end openings at the other end of said tube means terminating in a common plane where they are connected to a common collecting flange to form an outlet for said one fluid medium, said tube planes being spaced from one another in parallel relationship by spacing strips extending transversely to the longitudinal extent of the tube means and arranged adjacent the respective rectangular end openings to form a tube floor for the tubes of one plane, said strips being of a thickness corresponding to the rectangular height of the tube ends and wherein alternate strips are folded over on themselves at their ends to abut the first tube means of the adjacent tube plane for staggering the tube means of one plane with respect to the tube means of another plane.
 2. A heat exchanger according to claim 1, characterized in that said housing has a curved interior configuration in the area adjacent the respective ends of said spacing strips.
 3. A heat exchanger according to claim 2, characterized in that the bar means are provided at the ends thereof with slots, by means of which they are adapted to be inserted into flange means at the housing means.
 4. A heat exchanger according to claim 1, characterized in that the strips exhibit slots at their ends for engagement with the collecting flanges of the housing and in that the outermost strip is provided with an inclined clamping surface to aid in the assembly of the tube means within the housing.
 5. A heat exchanger according to claim 1, characterized in that inlet and outlet means for the other fluid medium are arranged laterally directly adjacent the bottoms of the rectangular cross section portion of the tube means.
 6. A heat exchanger according to claim 4, characterized in that inlet and outlet means for the other fluid medium are arranged laterally directly adjacent the bottoms of the rectangular cross section portion of the tube means.
 7. A heat exchanger according to claim 1, characterized in that each of the tube means is cylindrical along a substantial portion thereof and that the tube means of two adjacent planes are mutually offset by an amount corresponding to approximately the diameter of the tube means.
 8. A heat-exchanger according to claim 7, characterized in that said housing has a curved interior configuration in the area adjacent the respective ends of said spacing strips. 